Description

Find_first_of is similar to find, in that it performs linear
seach through a range of Input Iterators. The difference is that
while find searches for one particular value, find_first_of
searches for any of several values. Specifically, find_first_of
searches for the first occurrance in the range [first1, last1)
of any of the elements in [first2, last2). (Note that this
behavior is reminiscent of the function strpbrk from the standard
C library.)

The two versions of find_first_of differ in how they compare
elements for equality. The first uses operator==, and the second
uses and arbitrary user-supplied function objectcomp. The
first version returns the first iterator i in [first1, last1) such
that, for some iterator j in [first2, last2), *i == *j. The
second returns the first iterator i in [first1, last1) such that,
for some iterator j in [first2, last2), comp(*i, *j) is true.
As usual, both versions return last1 if no such iterator i
exists.

Definition

Defined in the standard header algorithm, and in the nonstandard
backward-compatibility header algo.h.